This invention relates to a copying apparatus employing a solid imaging device.
Conventionally, there is known an copying apparatus utilizing an electrophotographic system in which a surface of an original subject is scanned with a light, a solid imaging device such as CCD (Charge Coupled Device) is illuminated with a reflecting light from the original subject, then a bit map image data converted in the CCD is temporarily stored in a memory. A circumferential surface of a photoconductive drum is exposed to the light such as laser beam which is ON/OFF modulated in accordance with the data stored in the memory so as to form a latent image on the drum surface, a toner is then sprayed onto the latent image surface, and the toner image is transferred onto a recording medium (paper).
In the CCD, electric charge photoelectrically converted by an photoelectric conversion device is stored in an electric charge storage composed of junctions of semiconductor devices. By controlling the potential of the semiconductor devices, the electric charge stored in each condenser is output in sequence.
However, the amount of the surface charge stored in the CCD is too small to allow some work to be externally done. Likewise, when large amount of light is exposed to the CCD, it is easily saturated and thereby a wide dynamic range cannot be obtained.
Moreover, since electric charges are serially moved by controlling the potential of the CCD as described above, the loss of electric charge during the movement thereof is not constant. Consequently, even if the CCD receives the same amount of light at any position on the surface thereof, the amount of electric charge photoelectrically converted at each position depends on the position where the light is irradiated.
Furthermore, in the conventional copying apparatus, because a process for scanning the circumferential surface of the photoconductive drum is required as well as that for the surface of the original subject, it takes much time to record an image. In addition, since both the surface of the original subject and the circumferential surface of the photoconductive drum should be individually scanned, two exposure systems are required, thereby the construction of the copying apparatus is complicated.
An object of the present invention is to provide an improved solid imaging device having a matrix of electric charge storage of high capacity in which the loss of the electric storage charge amount can be independent of the position where light is irradiated. The light having an image data being irradiated onto the photoelectric conversion device is photoelectrically converted and stored in each electric charge storage of the solid imaging device disposed in accordance with each element of the photoelectric conversion device. By electrostatically spraying a toner onto the charged surface of each electric charge storage, an image can be copied with a single exposure system, thereby the structure of the device is simplified as well as made compact and the copying time of an image is reduced.
For this purpose, according to this invention, there is provided a copying apparatus employing a light source for illuminating an original subject to be copied and forming a toner image corresponding to the original subject on a recording medium, the apparatus comprises:
solid imaging means for converting a reflected light from the original subject into electric charge and for storing the electric charge therein, the solid imaging means being provided with a chargeable surface on which the electric charge is to be collected;
developing means for applying toner onto the charged portion of the surface of the solid imaging means to form a toner image; and
transferring means for transferring the toner image formed on the surface of the solid imaging means onto the recording medium.